Life on Earth was unlikely to have emerged from volcanic springs or hydrothermal vents, according to a leading US researcher.

Experiments carried out in volcanic pools suggest they do not provide the right conditions to spawn life.

The findings are being discussed at an international two-day meeting to explore the latest thinking on the origin of life on Earth.

It is taking place at the Royal Society in London.

Darwin's theory

David Deamer, emeritus professor of chemistry at the University of California at Santa Cruz, said ahead of his presentation: "It is about 140 years since Charles Darwin suggested that life may have begun in a 'warm little pond'.

"We are now testing Darwin's idea, but in 'hot little puddles' associated with the volcanic regions of Kamchatka (Russia) and Mount Lassen (California, US)."

Understanding how life emerged on Earth within 1,000 million years of its formation is a fascinating scientific problem

Prof Ian Smith, University of Cambridge

"The results are surprising and in some ways disappointing. It seems that hot acidic waters containing clay do not provide the right conditions for chemicals to assemble themselves into 'pioneer organisms.'"

Professor Deamer said that amino acids and DNA, the "building blocks" for life, and phosphate, another essential ingredient, clung to the surfaces of clay particles in the volcanic pools.

"The reason this is significant is that it has been proposed that clay promotes interesting chemical reactions relating to the origin of life," he explained.

"However," he added, "in our experiments, the organic compounds became so strongly held to the clay particles that they could not undergo any further chemical reactions."

Martian existence?

While our understanding of the world is rapidly increasing, the answer to how life began on Earth remains elusive.

The conference, involving more than 200 leading international scientists, will also explore other theories including whether life arrived from space.

Scientists see evidence of early life in ancient rocks

"It is presumed that life arose in a soup rich in carbon compounds, but where did these organic molecules come from?" said Dr Max Bernstein from the US-based Seti Institute.

He believes the answer may lie in interstellar dust, and will be talking about the possibility that a comet or asteroid may have provided Earth with the raw ingredients needed for life.

The researchers will also be asking whether life could exist elsewhere in the Universe.

Professor Monica Grady, from the UK's Open University, will explore the possibility of a Martian existence at the meeting.

She will discuss whether a Martian biosphere once existed by examining research into the carbon chemistry of Mars.

Professor Ian Smith, from the University of Cambridge, the organiser of the conference said: "Understanding how life emerged on Earth within 1,000 million years of its formation is both a fascinating scientific problem and an essential step in predicting the presence of life elsewhere in the Universe."

Professor Deamer said that his research, which is not yet published, will help to narrow down the theories about how life on Earth emerged.

"One possibility is that life really did begin in a 'warm little pond', but not in hot volcanic springs or marine hydrothermal vents," he added.